1. Field of the Invention
The present invention relates to a charge system and a charger for an electric apparatus, and a control method thereof. More particularly, the present invention relates to a charge system and a charger for an electric apparatus, and a control method thereof, in which a rechargeable battery mounted on the electric apparatus and another rechargeable battery mounted on an external charger are sequentially charged and discharged.
2. Description of the Related Art
Recently, portable electric apparatuses such as notebook computers, cellular phones, a personal digital assistants (PDAs), MP3 players and the like have increased in popularity. Typically, lithium ion batteries, a nickel metal hydride (NiMH) batteries, a nickel cadmium (Ni—Cd) batteries and other various rechargeable batteries are used as a power source for the electric apparatus.
If the rechargeable battery is mounted on a conventional electric apparatus, the electric apparatus is provided with a charging circuit which receives direct current (DC) power converted from alternating current (AC) power through an AC/DC converter (usually referred to as an adapter) charging the rechargeable battery DC power. Moreover, if a separate rechargeable battery is added in order to use the electric apparatus as long as possible, the separate rechargeable battery should be charged through a separate external charger connected to the AC/DC converter. Alternatively, the electric apparatus and the charger can be connected to two separate AC/DC converters, respectively. In this case, the respective rechargeable batteries are charged independently of each other.
Meanwhile, when the rechargeable battery mounted on the electric apparatus is discharged as the electric apparatus is used, and thus its voltage falls below a predetermined level, the mounted rechargeable battery that is completely discharged is usually replaced by the separate rechargeable battery that is charged using the separate charger.
Therefore, a need exists to make the rechargeable battery mounted on the electric apparatus be easily charged, and make the use time of the electric apparatus last as long as possible.